This invention relates to reduction of counterweight size in electric motor driven rotating machinery. Counterweights are used widely in rotating machinery applications to counteract unbalanced forces of eccentrically rotated machinery components. Known counterweights often occupy a substantial amount of space within a rotating machinery extending both radially outward of the rotating shaft and axially along the shaft length. Examples of such rotating machinery for air conditioning and refrigeration application include scroll and rotary vane compressors.
While this invention is equally applicable to both scroll and rotary vane compressor, the application of this idea is illustrated on a scroll compressor. It should be understood that a worker of ordinary skill in the art would recognize the application of this idea to other types of compressors.
Scroll compressors are widely utilized in refrigerant compression applications. In a scroll compressor, a pair of scroll members each have a base and generally spiral wrap extending from the base. The wraps interfit to define compression chambers. One of the two scroll members is driven by a rotating shaft to orbit relative to the other. Because the orbiting scroll is positioned eccentrically on the rotating shaft, the scroll orbiting movement creates force imbalance. Scroll compressors have historically been manufactured with a relatively massive counterweight attached to the shaft or electric motor rotor to counteract this force imbalance and thus minimize scroll compressor vibration.
It is often desirable to reduce the required housing size of scroll compressors. However, the relatively massive counterweight has restricted the ability to reduce the size of the scroll compressor housing.